1. Field of the Invention
The present invention relates to a method for inhibiting the autophagy of motor neurons, especially for delaying the onset of motor neuron degenerative diseases and/or curing motor neuron degenerative diseases.
2. Descriptions of the Related Art
A neuron, also known as a nerve cell, is one of the structural and functional units of the nervous system of the organism. Neurons can transmit messages to other cells by chemical and electrical signals. Neurons can vary in shape and size, and the diameters of neurons may range from about 4 μm to about 100 μm. The structure of a neuron can be roughly divided into three parts: a cell body, dendrites, and an axon, wherein dendrites can transmit signals into cell bodies, and axons can transmit signals out from cell bodies.
Neurons can be classified into three types depending on the direction of their signal transduction and functions: sensory neurons, motor neurons and interneurons, wherein a motor neuron is a nerve cell controlling the body activities of an organism. In general, motor neurons in the brain are known as upper motor neurons, while motor neurons in the brain stem and the spinal cord are known as lower motor neurons. Functional disorders caused by the degeneration of motor neurons may result in motor neuron degenerative diseases, such as amyotrophic lateral sclerosis (ALS), myasthenia gravis, myasthenia, muscular atrophy, muscular dystrophy, multiple sclerosis, multiple-system atrophy, spinal muscular dystrophy, etc. Patients suffering from the aforesaid motor neuron degenerative diseases will gradually show symptoms such as muscle weakness, atrophy, trembling, cramping rigidity, which may lead to difficulty speaking, difficulty swallowing, and respiratory failure.
The real cause of motor neuron degenerative diseases is still uncertain to date. However, research has shown that the possible causes of the disease include neuronal death caused by excessive autophagy stimulated by the accumulation of superoxide anions, autoimmune disorder, excessive neuronal excitation (e.g., excessive accumulation of glutamates), excessive oxidation, and heredity, etc. The medicines presently used in clinic to treat motor neuron degenerative diseases include glutamate antagonists such as Riluzole, antioxidants such as vitamin E, neurotrophic factors, immune modulators, etc. However, the aforesaid medicines usually do not have significant therapeutic effect or may only lengthen the life of the patients for 3 to 6 months. Therefore, there is still a need for a medicine to delay the onset of motor neuron degenerative diseases and/or cure motor neuron degenerative diseases.
The inventors of the present invention found that the compound of formula (I) of the present invention can be used to inhibit the autophagy of motor neurons and decrease motor neuronal death, thereby, delaying the onset of motor neuron degenerative diseases and/or curing motor neuron degenerative diseases.